Pass the IAsyncResult object returned by the current method to EndWrite to ensure that the write completes and frees resources appropriately. You can do this either by using the same code that called BeginWrite or in a callback passed to BeginWrite. If an error occurs during an asynchronous write, an exception will not be thrown until EndWrite is called with the IAsyncResult returned by this method.

If a stream is writable, writing at the end of the stream expands the stream.

The current position in the stream is updated when you issue the asynchronous read or write, not when the I/O operation completes. Multiple simultaneous asynchronous requests render the request completion order uncertain.

If a stream is closed or you pass an invalid argument, exceptions are thrown immediately from BeginWrite. Errors that occur during an asynchronous write request, such as a disk failure during the I/O request, occur on the thread pool thread and throw exceptions when calling EndWrite.